Noiseless one-way clutch mechanism for the silent return of the paper carriage in writing machines



Apnl 11, 1939. F. WUNDERLICH 2,153,735

NOISELESS ONE-WAY CL H MECHANISM FO SILENT RETURN OF THE PAPER RIAGE IN WRITI HINES Filed March 19, 1957 j? Wande /14A Patented Apr. 11, 1939 UNITE]? STATE-S PATE OFFICE carcass Y NOISELESS ONE-WAY MECHANISM FOR THE SILENT RETURN OF THE PAPER CARRIAGE IN WRITING MACHINES Fritz Wunderlich, Nuremberg, Germany, allignor to the firm Triumph-Wake Number: A.-G.,

Nuremberg, Germany Application March is, 1m, Serial No. 131,948 In Germany March 20, 1936 2 Claims. (01. 192-45) returning the paper carriage silently in writing.

machines. With these known arrangements spring pawls are in general provided, which engap between two of the teeth I2 is so arranged that it lies outside the circle struck from the centre of the rivets or studs 6, -1 with the radius of the cylinder,

gage in escapement or ratchet wheels, and which The rotary keys 8 and 8 are provided with holes 5 are brought into and out of engagement by means l5 and IS, in which there engage springs l1 and of frictional members or like devices. The disl8, which are secured to the escapement wheel 4 advantage of this carriage return resides in the at l9 and i8, Furthermore the rot ry keys are fact that the left-hand writing. margin becomes recessed by providing cavities 20 and 2|. uneven, since the pawl or the loose ratchet tooth This apparatus operates in the fol w n n- 10 frequently does not engage with certainty. The ner: By the action of the springs I1 and I8 the letter at the beginning of the line then only makes rotary keys, as shown in the case of the rotary its impression at the second or third position. key 9, are in general held in a position in which Furthermore with these devices a. loud noise 00- the centre line of the spring passes through the curs when the carriage is drawn back. axis of the stud I. Now if, during the return of The present invention obviates these disadvanthe carriage, the coupling wheel 3 moves in the tages by mounting on the escapement wheel cyl direction of the arrow in Figure 3, the rotary key indrical rotary keys which are rotatable about the 9, at first remains in the position represented axis of the cylinder, and which are formed with in Figure 1, until the next tooth "strike: against a recess, and can oscillate about a mid position the lower porti f he recess I in the rot ry 20 given by a tension spring in such a way that they key 9. The rotary key 9 is then rotated in a bear against curved surfaces provided on the counter-clockwise direction, stretching the spring coupling wheel, the radius of these curved surso that the ooth I2 can s p t ou h beneat faces corresponding to the radius of the cylinder. i Af er the t h h s Slipped through. t It is advantageous to select the position of the ry k y. y virt of i m m n m, swin 25 curved surface on the ratchet wheel in such a back somewhat beyond the mid position, as way that the rotary keys can swing past freely. shown in Figure 4. n is then r rned into its When the number of coupling possibilities is initial position again by the action of the spring large, it is advantageous to provide at least two l'i. If on the other hand the wheel 3 is rotated rotary keys on the-escapement wheel. The an- .in the direction opposite to that indicated by the 30 gular position of these in relation to the couarrow in Fig re 1, the Surface H of the toothed pling surfaces of the coupling wheel is such that wheel 3 bears against the cylindrical surface of only one of the rotary keys comes into engagethe rotary key 9 and the toothed wheel 2, which ment at a. time. is rigidly connected with the coupling wheel 3,

The invention is illustrated by way of example is thereby firmly coupled to the ratchet wheel 4. in the accompanying drawing, in which Since the contact surfaces between the curved Figure 1 shows the device according to the infaces I4 on the coupling wheel 3 and the pevention in elevation; ripheral surfaces of the rotary keys 8 and 9 have Figure 2 is a section on the line 2-2 in Figure 1, their centres of curvature at the axes of the keys, and the coupling wheel, when rotating in a counter- 40 Figures 3 and 4 show details in elevation. clockwise direction, has no tendency to rotate the Upon a stationary shaft I the toothed wheel 2 keys about their pivots. All that the springs have of the carriage is rotatably mounted. This wheel to do, therefore, is to return the rotary keys to is rigidly connected with a coupling wheel 3. their mid positions when released after being dis- There is also rotatably mounted upon the shaft placed. I an escapementwheel 4 with ratchet teeth 5. It will therefore be realized that thetension Upon this escapement wheel rotary keys 8 and 9 in the springs I1 and I8 need only be very slight. are mounted by means of rivets or studs 6 and When the coupling wheel is rotating in the direc- 1 respectively, these keys being cylindrical in tion of the arrows inFigures 1, 3 and 4 the teeth shape, with recesses ill and II respectively. l2 do not strike a direct blow against the key 8 The coupling wheel 3 has teeth l2, which, on or 9 and knock it aside but meet it at an angle the side opposite to the free running direction, and displace it progressively. Moreover the rehave curved faces l4. These faces have the same sisting torque produced by the spring is a miniradius of curvature as the cylindrical faces of mum when the tooth meets the curved surface the rotary keys 8 and 9. The portion ll of the of the recess II. It mayeven happen, owing to ure 1, are so arranged that thereis always only one rotary key engaged. The number of teeth of the coupling wheel 3 can thereby be materially reduced. This number is equal to the number of teeth of the escapement wheel 4 divided by the number of rotary keys.

What I claim is:

1. A noiseless return mechanism for the paper carriage in writing machines, comprising a stationary pivot mounted fast in the writing machine, a toothed coupling wheel rotatable upon the stationary pivot, an escapement wheel rotatable upon the stationary pivot, at least one substantially cylindrical key rotatably mounted eccentrically 'on one side of the escapement wheel, concave faces on the teeth of the coupling wheel, the radius of curvature of these concave faces being equal to that of the cylindrical key, a tension spring secured at one end to the escapement wheel and at the other end to the rotatable key to hold the key normally in a mid position to 'either side of which it can rotate by stretching the spring, and the concave faces on the coupling wheel being adapted in certain positions to bear against the periphery of the rotatable key, the.

rotation, and the radius of the peripheral surface of the coupling wheel in the spaces between its teeth, plus the radius of the cylindrical key,

arcane being may lessthan the distance between their axes, so that the key can oscillate past, its con- Y tact position.

2. A noiseless return mechanism for the paper carriage in writing machines, comprising a stationary pivot mounted fast in .the writing machine, a toothed coupling wheel rotatable upon the stationary pivot, an escapement wheel rotatable upon the stationary pivot, at least two substantially cylindrical keys rotatably mounted eccentrically on one side of the escapement wheel, a tension spring for each of the rotatable keys, each spring being secured at one end to the escapement wheel and at the other end to the rotatable key to hold the key normally in a mid position to either side of which it can rotate by stretching the spring, and concave faces on the teeth of the coupling wheel, the radius of curvature of these concave faces being equal to that of the cylindrical keys, the concave faces on the coupling wheel being adapted in certain positions to bear against the periphery of the rotatable keys, each rotatable key being formed with a recess in its periphery to permit the teeth of the coupling wheel to deflect it and pass it in one direction of rotation, the radius of the peripheral surface ofthe coupling wheel, in the spaces between its teeth, plus the radius of either cylindrical key, being slightly less than the distance between the axis of the coupling wheel and the axis of the key, so that the key can oscillate past its contact positlon, the keys beng in staggered relationship to the concave surfaces of the coupling wheel, so that only one of the keysat a time can bear with its cylindrical surface against a concave surface on the coupling wheel, and the number of teeth on the coupling wheel being equal to the number of teeth on the escapement wheel divided by the number of rotatable cylindrical keys.

FRITZ WUNDERLICH. 

